I agree that the Railroads would not create a switchback situation like that if they could avoid it. they would certainly not do it on their tracks.
However, industries in tight spots did/do all sorts of things to get track into or next to a building. So as an industrial track, I don't think the switchback is unprototypical. Look at photos of industrial trackage in towns and cities.
I think a coalmine takes a lot of space and you are a little limited. I would skip the mine if it were me, but put in some coal customers such as a coal yard when they were still common. Then you can deliver loads off the interchange to the coal customers and send empties back, but the number of cars would not be so many and the space required much smaller. A lot smaller industries used coal for running steam heat plants or even generators for years. The Charmin paper plant in Hamilton Ohio had a coal fired plant that used 4 hopper loads a day. Unfortunately their unloading track only held 2, so it had to be switched twice a day. A very good friend of mine ran the shortline RR that switched the plant and told me about operations there.
Whether you keep the yard or not is pretty much what you like and how you want to operate. You might think about what the trains will do and how they will run for operations and base your decision on that. At the size of your RR, I could go either way. If it had a few more industries, I would keep the yard. But also you could get another goodsize industry on the peninsula and keep one yard track.
Email me about some information on switchlist software if interested. Your email is not in your profile.